The present invention relates to a failure detecting device ant method for a radio transceiver apparatus and, more particularly, to a failure detecting device and method for detecting a failure in an outdoor reception amplifier unit of the radio transceiver apparatus.
As shown in FIG. 3, a conventional failure detecting device of this type is designed such that an indoor transceiver unit 20 always monitors whether an outdoor reception amplifier unit 10, arranged outdoors together with an antenna 30, is operating normally.
The outdoor reception amplifier unit 10 includes an antenna sharing unit 11, a pilot signal generator 13, a hybrid circuit 12, and a reception amplifier 14. The antenna sharing unit 11 demultiplexes a transmission signal S8 transmitted from a transmitter 21 of the indoor transceiver unit 20 to the antenna 30, and also demultiplexes a reception signal S1 received by the antenna 30 to the hybrid circuit 12. The pilot signal generator 13 generates a pilot signal S2 used to determine whether a failure is detected. The hybrid circuit 12 combines the reception signal S1, demultiplexed by the antenna sharing unit 11, and the pilot signal S2. The reception amplifier 14 amplifies a signal S3 obtained by the hybrid circuit 12, and transmits the amplified signal, as a signal S4, to a receiver 22 of the indoor transceiver unit 20 and another receiver (not shown).
The indoor transceiver unit 20 includes the receiver 22, an electric field detecting section 23, and a failure detecting section 24. The receiver 22 transmits reception signal information S5 to the electric field detecting section 23 upon tuning the reception signal information S5 to the frequency of the signal S3 contained in the signal S4 and transmitted from the pilot signal generator 13. The electric field detecting section 23 detects the electric field strength of the pilot signal S2 tuned/received by the receiver 22, and outputs electric field strength information S6. The failure detecting section 24 compares predetermined reception electric field strength information of a pilot signal with the actual electric field strength information S6 of the pilot signal received by the electric field detecting section 23 to check whether the reception amplifier 14 of the indoor transceiver unit 20 is operating normally. If it is determined that the reception amplifier 14 is operating abnormally, the failure detecting section 24 outputs failure information S7.
A failure detecting operation of the device having the above arrangement will be described next.
The pilot signal S2 generated by the pilot signal generator 13 is used as a target value to be always monitored to check whether the reception amplifier 14 of the outdoor reception amplifier unit 10 is operating normally. The pilot signal S2 is combined with the reception signal S1 by the hybrid circuit 12, and the combined signal S3 is amplified by the reception amplifier 14 and supplied to the indoor transceiver unit 20. The reception signal S1 used for normal communication is received after being tuned to a reception signal frequency by a receiver (not shown) of the indoor transceiver unit 20. The receiver 22 receives the pilot signal S2 tuned to a pilot signal frequency and contained in the signal S4. The electric field strength of the pilot signal S2 received by the receiver 22 is detected by the electric field detecting section 23, and the electric field strength information S6 is supplied to the failure detecting section 24. A pilot signal electric field strength detection level is set in the failure detecting section 24 in advance in accordance with the output level of the pilot signal generator 13 for generating the pilot signal S2 and the amplification factor of the reception amplifier 14. The failure detecting section 24 compares this detection level with the electric field strength information S6 actually supplied from the electric field detecting section 23. If there is a difference of a predetermined value or more, the failure detecting section 24 determines that a failure has occurred in the reception amplifier 14, and outputs the failure information S7.
In this conventional failure detecting device, the pilot signal generator 13 for generating a pilot signal as a means for detecting a failure must be arranged in addition to the pilot signal generator required for the transceiver apparatus, resulting in an increase in the cost of the unit.
Since the standard value of the output level of the pilot signal generator 13 is used, when the output level varies due to a failure in the pilot signal generator 13, failure information is output, even though the reception amplifier 14 is operating normally. For this reason, periodic maintenance is required to ensure the normal operation of the pilot signal generator 13. In addition, since the outdoor reception amplifier unit 10 is fixed to a high installation place such as a steel tower owing to its function, the cost for periodic maintenance of the pilot signal generator 13 is high.